Nonpoint sources

P. S. C. Rao andj. M. Davidson, in M. R. Overcash andj. M. Davison, eds.. Environmental Impact of Nonpoint Source Pollution, Ann Arbor Science Pubhsher, Ann Arbor, Mich., 1980, pp. 23—67. 

R. E. Smith, Opus An Integrated Simulation Modelfor Transport of Nonpoint-Source Pollutants at the Field Scale, Vol. I, Documentation, USDA ARS-98, U.S. Dept, of Agriculture, Washington, D.C., 1992. 

The principal inputs can be divided into two broad categories point sources and nonpoint sources. The point inputs are considered to luive a well-defined point of discharge, wliicli under most circumstances is continuous. A... 

The results of map generation cannot be expressed effectively with the format available here. However, the State of Oregon utilized the map and matrix techniques in their nonpoint source evaluation and as a basis for designing more intensive survey approaches to assessing the impact of human activity on river quality. In addition to reflecting deposition of sediments, the methods can be applied to transport of pesticides, nutrients and trace elements since many of these substances tend to adsorb to the organic and inorganic fractions of soil. 

For an aquatic model of chemical fate and transport, the input loadings associated with both point and nonpoint sources must be considered. Point loads from industrial or municipal discharges can show significant daily, weekly, or seasonal fluctuations. Nonpoint loads determined either from data or nonpoint loading models are so highly variable that significant errors are likely. In all these cases, errors in input to a model (in conjunction with output errors, discussed below) must be considered in order to provide a valid assessment of model capabilities through the validation process. 

Borah DK, Bera M (2004) Watershed scale hydrologic and nonpoint source pollution models review of applications. Trans ASAE 47(3) 789-803... 

Trim, A.H. 1987. Acute toxicity of emulsifiable concentrations of three insecticides commonly found in nonpoint source runoff into estuarine waters to the mummichog, Fundulus heteroclitus. Bull. Environ. Contam. Toxicol. 38 681-686. 

Pesticides in wastewaters come typically from point sources of contamination such as disposal sites and landfills where industrial or agricultural wastes are buried without any consideration, as well as discharges from industrial effluents from pesticide production plants. Furthermore, nonpoint sources derived from regular agricultural activities, especially in intensive agricultural areas, and accidental spills can also be significant. Urban use of pesticides is also possible in large cities where the use of herbicides and insecticides may result in runoff into the sewers. These sewers in turn may expel pesticides into wastewater treatment plants (WWTPs). 

Millions of soil samples per year are analyzed for nonpoint source analytes such as potassium, phosphorous, insecticides, and herbicides. It is necessary to obtain an idea of the level of these components throughout the field and to take corrective action as necessary. Thus, a more random sampling methodology is called for. Figure 7.2 shows a field that includes both different soil types (letters) and topographical features (e.g., a ditch) that are to be sampled. Also, a transect line and locations of sample sites along it are indicated. Transect lines and sampling sites are discussed later. 

Nonpoint source sampling occurs where the analyte of interest is dispersed over a large area such that a specific point of origin cannot be ascertained. The innate occurrence of analytes of interest would be an example of a nonpoint source. The occurrence of plant nutrients, either naturally occurring or from fertilization, is an example of a nonpoint source of agricultural analytes. Herbicides, insecticides, and pest-control agents are, once applied on a field scale, also potential nonpoint sources of analytes. It is common to think of crop... 

Figure 7.7. Transect sampling for a nonpoint source analyte. 

Transect sampling for nonpoint sources is done the same way and with the same purpose as it is in point source sampling. Figure 7.7 shows a transect across an area to be sampled. Different markers indicate that different sampling will be accomplished at these sites. These would also be sites for depth sampling if it is called for. 

Describe the differences in sampling procedures that would be used when sampling point source and nonpoint source contaminations. Are there any methods of analysis that would be common to both situations ... 

Hexane is probably released to water from a number of sources including industrial discharges, effluents from municipal waste-treatment plants, and nonpoint-source runoff from roads and other surfaces. Insufficient information is available to quantify the releases in a comprehensive fashion. 

Marsh JM. 1993. Assessment of nonpoint source pollution in stormwater runoff in Louisville, (Jefferson County) Kentucky, USA. Arch Environ Contain Toxicol 25 446-455. 

There are numerous sources that release cyanide into water. Cyanide is released into water from both point and nonpoint sources. The major point sources of cyanide released to water are discharges from publicly owned treatment works (POTWs), iron and steel production, and organic chemical industries (Fiksel et al. 1981). Estimates based on data from the mid-to-late 1970s indicate that these sources account for 89% of the estimated 31 million pounds of total cyanide discharged annually to surface... 

Rao PSC, Davidson JM (1980) In Overcash MR, Davidson JM (eds) Environmental impact of nonpoint source pollution. Ann Arbor Science Publishers, Ann Arbor, MI, pp 23... 

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